Apparatus for handling materials



May 30, 1933. A. sAURBRl-:Y

APPARATUS FOR HANDLING MATERIALS 5 sheets-Sheet 1 Filed May 13, 1951 May 30, 1933. A. sAURBRl-:Y

APPARATUS FOR HANDLING MATERIALS Filed May 13, 1931 5 Sheets-Sheet 2 May 30, 1933. A. sAURBREY APPARATUS FOR HANDLING MATERIALS- Filed May l5, 1951 5 Sheets-Sheet 3 INVENTOR May 30, 1933. A. sAURBRl-:Y 1,911,397

APPARATUS FOR HANDLING MATERIALS Filed May 13, 1951 5 Sheets-Sheet' 4 Lf www May 30, 1933. A. SAURBREY APPARATUS FOR HANDLING MATERIALS Filed May 13, 1951 5 Sheets-Sheet 5 INVENTOR Patented May 30, 1933 NT ori-"ice i ALEXIS SAURBREY, OF PITTSBURGH, PENNSYLVANIA APPARATUS FOR HANDLING MATERIALS Application led May 13,

The invention relates to an apparatus for handling and conveying divided materials such as concrete, gravel, dry sand, crushed stone, coal, and coke. The invention is illustrated and described as applied to apparatus for receiving material from a bin or hopper mounted over the apparatus, and transporting it to a container, such as a form, some distance away, both horizontally and vertically, using a iiuid such asV air for the transporting medium. Such machines using compressed air for conveying concrete have been used for many years, and I do not broadly claim the use of compressed air for this purpose. However, trouble has been experienced with such machines to a great extent, partly because the receiving gates would fail to operate 'in a satisfactory manner, and partly Vbecause the discharge line would clog, thus, making the machine inoperative. In actual operation, it has also been found that'pre- Vious machines caused considerable segregation of material, delivering the linemaz5terial of the concrete at a place and time distinct from the coarser material causing honeycomb and. streaks inthe resulting concrete. In tunnel work, where these machines have found their greatest application and use, all these objectionable features assume great importance. Thisarises from the restricted space available in tunnels `for the operation of any" construction machinery employed therein, making it both tedious and expensive to take a clogged line apart to clean 2 it, `or to make adjustment of any kind to a stuck orworn gate. The principal object of the present inventionis to entirely eliminate the foregoing diiiculties, namely, the avoid- 40 j anceof any tendency of the material to separate or clog, and any tendency of the doors or gates to stick. The invention has for its further objects the provision of a machine which can be easily controlled bya single4 operator; which requires a minimum amount of compressed air; andwhich will convey a maximum amount of material in a given pe-V riod of time. Certain embodiments of the invention are shown in the accompanyingA regulated by the operator through the hand-le '20,' link 21, and lever 22.` Air pressure is 100 drawings, wherein: v A Figure 1 is `a side elevation ofthe appa- 1931. sei-iai No.: 537,080.

ratus, showing two of the gates in closed position. Fig. 2 isa partial side elevation showing the two gates in open position. Fig. 3 is a section on the line III-III of Fig. 1. Fig. 4 is a plan View with the hopper or bin 55. removed. Fig. 5 is a section ion the line V-V of Fig. 1. Fig. 6 is a vertical section through the gate at the top of the casing. Fig..7 is an enlarged section through the casing. Figs. 8 and 9 are enlarged detail 60 views of the gate clamping devices. Fig. 10 is a detail section on the line X-X of Fig. 7. Fig. 11 is a detail perspective view. Figs. 12 and 13 are sections through a vmodification. And Fig. 14 is a section through an- 65 other modification. i 1

Referring to the drawings, l is a framework provided with wheels 2 and mounted on tracks 3; 4 is a cylindrical casing mounted upon the Aframework as later described and 70 provided with theslide gate 5 at its upper end and the swinging gate or valve 6 at its lower end; 7 is a drum mounted for rotation in the casing upon the bar 8; 9 is a hopper v or bin located above the casing and provided with a swinging gate 10; 11 is a conduithaving an Venlargement/or boot 11a at its end. leading from the lower end of thecasing for conveying material, such as concrete to any desired point of use; 12 is an aircylinder B0 for operating the gates 5 and 10; 13 is a compressed air tank for supplying air toA the manifold 14 and thence to the casing 4, the conduit 11, the auxiliary tank 13a andthel cylinder 12, such tank being itself supplied 85 with air by means of a motor and compressor, not shown; and 15 is the operators seat from which the air valve handles 16 and 18 are accessible as wellas the foot control 19. g

The apparatus is so arranged that the operation of the cylinder 12 opens the gates 5 and 10 successively, permitting a discharge from the bin 9 to the casing, after which thev gates 10 and are closed successively. The charge passing into the casing is received by the drum 7 which now rotates through about degrees vso that the material flows onto the door or gate 6 whose degree of opening is applied to the drum and conduit by means of the pipes 23, 24 and 25, all communicating with the tank 13 and controlled by the valves operated by the handle 18 and the foot treadle 19. These sources of air supply may be operated together or in any desired sequence at the discretion of the operator after the gate 5 is closed. lThe pintle 26 of the gate 6 is preferably hollow and communicates with a cavity in the gate itself which has perforations 27 (Fig. 7) through its face so that fluid, either air or water, separately orat the same time, may be supplied through such perforations. Flexible pipes 28, 29 (Fig. 10) are conn-ected to the ends of the pintle, one of which may be connected to the tank 13 :and the other toa source of water pressure controlled by suitable valveswhich are not shown. The directing of the conduit 11 upwardly from the bottom ot the contain-er, as shown, is of advantage over a conjoint, as later described. The gate 5 has flanges 32, 32 lying beneath the flanges 31,31,

yand when the gate approaches closed position, these flanges are forced upward to compress the packing and thus prevent leakage. This is accomplished by the pairs of rocker arms'33, 33 (Figs. 8 and 9). They are normally swung to the left by springs'34 (Fig.

l8), but when the gate approaches closed posi' tion, as indicated in Fig. 1, the flanges 35 and 36 on the gate engage the arms and swing them to the right, thus forcing the gate upward and 'compressing the packing strips31. Other liexible packing strips 37 and 38 are provided at the ablev flanges thereon and on the top of the casing, so that when the gate is pulled tightly shut, it is securely seated against leakage on all four sides. Y. y Y The'swinging gate 10 is operated. from the gate 5 by means cfa Vpair or" links 39 pivoted at 40 and 41. The` linksare each made up yof a pair of telescopic membersi42 and 43 'with a Compression spring therebetween the arrangement being such that the spring isr under compression when the gates are closed.

The Vgate 10-is thus closed in advance of theA- gate 5 and opened after it. vThe spring closure of thegate 10 prevents breakage in` case an obstruction, such as a large piece of material, blocks the gate 10 open. iThe opening ot thegateV 5 before the gate 10 opens ',avoids the vdeposit of material on thel gate.

ends kot the gate between suit- Y The gate 10 is also provided with a protruding lip 44 which overlaps the lip 44a and cuts oft material ahead of the closingy of such gate. On the opening movement of the gates, the dropping of material is delayed until the gate 5 is open, thus keeping the latter gate clean.

The gate 5 is opened from the cylinder 12 provided Vwithv the piston 45 and the rod 46. The rod is connected to a link 47 provided with a pin 48 working in a slot 49 in the end of the gate 5, thus providing a lost motion Yconnection between the gate and link 47. When air is admitted behind the piston 45, by moving the valve handle 16 to the position shown, the gate 5 is ymoved to the open position of Fig. 2, thus opening the gate 10.Y

When the air is released from behind the plunger, by moving theV valve handle to vertical position, thus cutting olf the supply of air from the :manifold 14 and venting the air from behind the piston to the atmosphere, a counterweight 48?) attached to the end of the gate by the cable 48a moves the gate back to the positionof Fig. l.

The further movement of the link 47 vby the piston 45 also controls the swinging movement of the drum 7 from the` position shown in Figs. 1 and 7 (with its opening up) to one at 180 degrees thereto (with its opening down) and back again as presently described. The drum is pivotally mounted on the transverse rod 8` (Fig. 3) which extends through the walls of the casing 4l and acts as a stay rod tor such walls. VThe drum isl rocked from one position to the othery by means ot a lever 51 pivoted lat 52upon a bracket secured to the casing 4. A shaft 53v extends through thel side wall of thecasing 4 in suitable air tight bearings and has secured toits ends Vthe lever arms 54 and v55 (Fig. 11) the former lying inside the casing and the latter outside of it, and connected to the lever 51 bythe link 56. Thelever 54 has at one side ot' its end a knob lor ball 50 lying between the cleats 57, 57 secured to the outer face of the drum. A counterweight V rection from theV position shown in Fig. 1 to Y one in which its opening is in registry with the outletrat the bottom of the casing 4., When the lever 51 is moved back kto the position shown, the drum will be rotated back to its starting position with its opening next to the gate 5.

The upper end of the lever 51 is'heldin the position shown by the keeper or` latch,

59carried by the bin 9, and normally pressed down by the spring '60. After the gate is i closed by the link 47, as heretoforedescribed,

the movement of the link 47 to vthe right is continued, due to the admission to thecyl-v in'deril2v on the left fof the piston 45 of a small amount of air from the pipe 61, which air is switched on when the valve handle 16 is moved to cut 0E the air to the right of the piston. This movement causes a lug 62 on the link to engage and lift the keeper 59, thus releasing the lever 51, so that the weight 58 acts `to swing the drum to discharge position with its outlet down, as heretofore described. If now air is admitted to the right of the piston 45, the link 47 is first moved tothe left, so that the lug 62 engages the upper end of the lever 51 andv moves it to the left until it reaches the position shown, and is engaged by the keeper 59. During this movement, the drum 7 is swung from discharge position back to charging position with its opening up. VDue to the pin and slot connection 48, 49 between the link 47 and gate 5, this return movement of the drum is accomplished before the gate starts to open. The drum is thus in position to receive the charge from the bin 9 by the time the gates 5 and 10 are in position to permit a discharge of material. As heretofore explained, the gate 5 is opened in advance of the gate 10 due to the spring connection, so that no discharge from the bin onto the top of the gate 5 can occur.

The air supplied to the casing 4 through the pipe 25 discharges against a bafile 63, as indicated in Fig. 7, so that a How of air is directed into the casing along the upper and lower faces of the swinging gate 6. This serves to clean the gate and prevents any material from lodging in the space beneath the gate and'interfering with its opening movement. An equalizing opening 63a also permits the passage of some air through the baffle and into the space between the drum and the casing. Air may be also supplied into the conduit. 11 from the pipe 24 having a valve controlled by the handle 18. This feed gives substantial assistance in moving lthe material through the pipe in case of any tendency toward stoppage. A pipe 23 connected to the pipe 25 serves to supply air to the upper portion of the drum acting as an equalizer and serving to give a pressure inthe upper portion of the drum approximating that inrlower portion, so that the material moves downwardV freely by gravity.

As shownin Fig. 7 packing means 64, 64

may be vemployed between the drum 7 and casing l4, so that when the opening in the drum is out of registration with the inlet to ther casing, the drum acts as an air tight gate for the inlet opening. This would permit the gate 5 to be'dispensed with, although Asuch gate is preferably used so that prac-A tically a double seal is secured against the escape vof air pressure from the casing.

The bootlla (which constitutes the g en-` i.

trance end of the conduit 11)', into which the casing. discharges, and which acts as the base` or support for the easing, is provided withV a bracket 65 pivoted at 66 on the horizontal members of the frame 1, and the other side of the boot is provided with a second bracket 67, which rests'V upon a spring 68 carried in a recess in one of the frame members. As the loading.l of the casing progresses, the casing settles about66 as a'pivot, compressing the spring 68. This movement is indicated by means of the armY 69 pivoted to the frame at 70 and to the casing at 71 and having its end movable over a scale 73, a keeper 72 being provided for guiding the movement ofthe arm. The operator by observing the arm is informed as lto the amount of charge in the casing. This is important because overloading results in preventing a proper closure of the gates and reduces the efficiency of the apparatus. As an additional safety device, the' arm 69 may be connected' by a rope 74 with the handle 16, so as to secure an automatic closure of the valve which admits air pressure to the right hand end of the cylinder 12. When this valve closes, the gate 5 closes and remains closed, so thatvthere is no further admission of material to the casing.

In operation, the operator, by means of the control handle 16, regulates the opening and closing of the gates 5 and 10, as heretofore described. Intermediate the opening movements of the gate 5, the drum swings from receiving position to discharge position and back again. The outlet gate 6 is adjusted to a position determined b y trial for varying conditions of operation; The material is fed from the casing and through the conduit 11 by the air supplied through the pipes 23 and i 24, and through the pintle 26 of the gate, the control of such air being regulated by the judgment of the operator. ater` is also supplied when desired through the pintle 26 to assist in cleaning the gate'and facilitating the flow ofjmaterial thereover. If the material handledis concrete and water is supplied at this point, the amount in the mixture in the bin 9 may be correspondingly reduce-d. -The feed 0f the material to and through the conduit 11 is accomplished byv the powerful ilow of 'airy from the pipe 25 directed' along the gate and toward vthe conduit so that there is no tendency to packr the material into the boot and stop the operation of the 1 machine. drum vabove the gate is only sufficient to equalize-the pressure so that'the material is deposited with-a-pressure on the gate6 only equal to that 'produced by gravity. Thismaterial isieasily ycarried laway as fast as it is deposited by the flow of air from the pipe 25. lVith some materials the pipe 23 may be dispensed with entirely and a satisfactory feed through the drum and conduit secured entirely by-gravity and by the cross feed as prol The supplyof air vinto thev and then opened.

g boot and conduit.

The drum 7 acts as a mixer, which miXing action may be increased by modifying the contour of the inner surface, as is well known in the mixer art. The move-ment f the drum back and forth, moves the material, and tends to prevent sticking in the casing. It Valso prevents any tendency lof the material to wedge in the boot 11a due to the impact of the material in falling. It thus acts as a baffle, and in performing this function needs to be only of an extent suflicient to cover the outlet opening to the boot, in which case it is necessary to have a movement of' oscillation only sufficienttocover the opening in one position and to discharge the material in another-position. My invention, therefore, conteinplates various modifications of the drum as to size, shape, and extentof oscillation. The

drum may also be entirely dispensed with, as later described more fully, in which case the material will fall directly from the bin 9 onto the gate 6. This gate will be normally kept open in anr adjusted position, but may be closed when the material is vdropped on it The use of this gate greatly reduces tlie tendeiicy'of the material to jam in the boot and stop the feed of the apparatus. The use of this gate is of particular advantage in this connection when the drum 7 is dispensed with as the tendency to jam is` greater under these conditions. The use of the air supply along the lower and upper sides of the gate and through it, further guards against any tendency to choke the This gate enables theoperator to feed material (as it is fed gradually by the drum) still more gradually into the boot. This isv of special importance in han- 1 dling sticky material, such as concrete, be-

cause material ofthis kind if once stopped,

is difficult to start, the tendency, under the application of pressure, being to wedge more firmly. The air as .supplied along thersur-y faces of the gate and through it acts as a l' lubricant, as well as a movingrforce.

The vertical riser pipe 11 serves as an air .lock compelling the rising air to force the -V ai material ahead of it, rather than over it, as sometimes occurs with a horizontal or sloping u delivery conduit, wherein the material may not lill the cross section of the conduit. The delivery of the material downwardly through the casing 4L by gravity saves power, as compared with 'a horizontal feed. The power operation of the gates 5 and 10 by a single power member, saves power and simplifies the work of the operator. The provisions for making the'y gate 5 tight, comprisingV the wedging arms 33, also adds to economy in Ithe use of air. The placing of the packing strips 31 so that they are outside the casing and protected.V from the' material .handled adds tothe life'ofV the closure meansand opening.

`Figs. 12 and 13 illustrate a simplified construction, heretofore referred to, lin which the rotating drum of the Fig. 1 construction is dispensed with so that the material admitted to the casing 7 a'falls directly upon the gate 6a. The air supply is accomplished by the pipe in conjunction Withthe pipes 23, 75, and`76, 76. An equalizing outlet 77 is also provided for supplying air to the upper portion of the casing. The pipes 76,76

discharge against the inclined walks 78, 784

of the casing, thus avoiding any tendency-of the material to collect at theseV points, and

promoting the feed into the boot.. The nov-v elty here residesV particularly in the flappergate and the air cavity-'or reservoir lying below the plate 63 and the gate.' It will be Y clear that when concrete is filled into the receptacle, there will remain a space not lle'd with concrete underneath the flapper gate..

than just that. It will be obvious that the' gate is so arranged that, when it moves, it simultaneously opens more for the air and closes more for the concrete. Therefore,

when a clog occurs in the discharge line, it isV j possible at one and the same time to choke rthe concrete and increase the air, and vice versa', when everything is .moving smoothly, to increase the concrete and choke the air.

The gate serves the further function of act-V ing as a pendulum,useful in breaking up a choking mass of concrete should one occur at the entrance to the boot. In practice, I

'have found it proper so to build the gate that there is a small open margin around the edge of the gate, as shown in Fig. 10, thus admitting air all around the edge o f the gate into the concrete'mass. This helps to surround the moving mass `of concrete in the delivery pipe 11 with an envelope ofair, thus materially lubricating the concrete and lassisting Ain its movement. In practice, I have found it best to adjust the gate once onlyfor each con'- sistency of concrete, Vand, to leave the gate at that opening or position, as long as the concrete does not change. It follows that ifthe apparatus is designed to be used with only a single consistency of concrete, the construction may be-siniplified and 'cheapened by making the gate merely a fixed partition having thedesired degree of inclination Yand Fig. 14 illustrates a further modification in which the casing 7b is supplied Vfrom the pipe 25 as in the-construction 'of Figsp12 and 13, and a pipe similarly leads to an equalizing outlet in the upper portion of the drums but in'which air is supplied to the inclined walls 78, 78 in a diderent manner. Here the air is supplied to the walls by a pairof nozzles 79, 79 connectedto the pipe 25 by means of the-pipes'SD, 80. j V Vhat I claim is:

l. In combination in a pneumatic conveyor, a casing having an inlet for material at its upperv side and an outlet at its lower side, a conduit leading from said outlet, a gate for said inlet, `means for supplying air under pressure to the casing, a drum mounted for rotation in the casing and provided Withan opening through one side adapted in one position of rotation to register with the inlet and in another position to register with said outlet, means for swinging the drum from one position to the other, means for opening andclosing said gate, and connections intermediate said means for operating the gatev and the means for swinging the drum whereby the swinging movement of the drum from position with its opening registering with said inlet and back to said position-occurs between the closing of the gate and its opening.

2. In combination in a pneumatic conveyor, a casing having an inlet for material at itsupper side and an outlet at its lower side, a conduit leading from said, outlet, a gateI for said inlet, means for supplying air under pressure to the casing, a drum mounted for rotation in the casing and provided with an opening through one side adapted in one position of rotation to register with the inlet and in another position to register with said outlet, and means controlled by the movements of the gate operating means for swinging the drum from one position to the other.

3.- -In combination in a pneumatic conveyor, a casing having an inlet for material at its upper side and an outlet at its lower side,

a conduitleading from said outlet, a gate for said inlet, a second gate at` the entrance to said conduit adapted tocontrol the flow of material from the casing to the conduit, and

Vmeans for `directing air under pressure along the surface of such second gate in the direction of the flow of the material.

`4. In combination in a pneumatic conveyor, a casing having an inlet for material at its upper side, and an outlet at its lower side, a conduit leading from said outlet, a gate for saidinlet, a? second gate pivoted at theentrance' to said conduit adapted to control the low'of material from the casing to the conduit, and means for directing air under pressure along the inner surface of such second gate toward the free end thereof. Y

5. In combination in a pneumatic conveyor, a casing having an inlet for material at its upper side, and an outlet at its lower side, a conduit leading from said outlet, a gate for said inlet, a second gate pivoted at the entrance to said conduit adapted to control the flow of materialfrom the casing to the conduit, and means for directing air under pressure along both surfaces of such 'second gate tOWard the lfree end thereof.; i s' 1 6. `In combination ina pneumatic conve-yor, acasing having an inlet formaterial at its upper side, and an outlet at its lower Aside, a conduit leading from said outlet, a gatefor said inlet, a swinging gate at the entranceto said `conduit adapted to control the flow of material Afrom-the` casing to the conduit, means for supplying air under pressure to the casing above thegate and other means for directingair under pressure intothe conduit alongv the lower side of` said swinging gate. l

7. Incombination in a pneumaticconveyor, a casing having an inlet for materialat its upper side and an outlet at itslower side, a conduit leading from said outlet, a gate for said inlet, means for supplying .air under` pressure to the casing, av second -gate at the entrance to said conduit having a hollow pintle and passagesv leading therefrom through they inner face of the gate, said gate being adapted to control the flow of material froml the casing tothe conduit, andvmeans for supplying .water under pressure yto said hollowv pmtle.

l8. In combination in a pneumatic con.-`

veyor, a casing havingan inlet for material at its upper side and an outlet-atits lower side, a conduit leadingdownwardly and lat-Y erally from the said outlet, agate for said inlet, means for supplying air under pressure to the casing, a swinging gate :at the entrance lof said conduit adapted to control the flow of material to ithe conduit, .means for adjustingthe position of the gate fronrl the exterior 'of the casing, said swinging a gate being pivoted at one .edge with, its free. edge extendinglaterally in thesame direc-,- tion as said conduit, and means'for supply-g` ing a separate How of airvunder pressure along the lower sident the swinging gate.

toward the free end thereof.

ceiving material to. be conveyedand a conduit leading therefrom, of a swingingrgate at the entrance of the conduit against which thematerial moves by gravt means` for directing aiow of air 'against such materialy the conduit, andmeans for directing another 10. In combinationl in apneumatic conveyor, a casing having an inlet for material and a-hopper bottomwvith'an outlet; a con-jf duit leading from 'said outlet, a gate at theV entrance of the conduit adapted to receive by gravity the m'aterialsupplied to the casi ing, means for ,directing a blast of air :longi-f 1 tudinallyof the gate into the conduit, Yand 2 `9. The combination withacasing for v1115 above the gate to carry ,itfroni thegate intoA means for directing Other blasts of air downwardly along the sloping sides of the hopper ,130,

bottom and through the gate.

11. In an'apparatus of the class described for handling material,'a` receptacle having a discharge line leading from its lower portion, such receptacle being divided by a pivoted gate into two unequal parts to which compressed air is supplied vand opening jointly into the discharge line, whereby material and compressed air are admitted simultaneously to the discharge line, with an increase in the supply of air to such line and a decrease in the supply of material thereto when the gate is moved in one direction, and a'decrease in the supply of air to the line and an increase in the supply of material thereto when the gate kis moved` in the other direction.

12. In an apparatus of the class described for handling material, areceptacle having a discharge line leading from its lower por tion, such receptacle being divided by a'pivoted gate into two unequal parts to which compressed air is supplied and opening jointly into the discharge line, whereby'material and compressed air areadmitted simultaneously to the discharge line, with an increase inthe supply of air to such line` and a Vdecrease inthe supply of material thereto when the gate is moved in one clirection, and a decrease 1n the supply ofair to the line and an increase in the supply of material thereto when the gate is moved vin the other direction, said gate having its 40 oted gate into two unequal parts to which compressed air is supplied and opening jointly into the discharge line, whereby material and compressed air are admitted simultaneously to the discharge line, with an .45,increase inthe supply of air to such line and a decrease in the supply of material thereto when the gate is moved in one direction, and a decrease in the supply of air to the line and an increase in the supply of material thereto when the gate isA moved in the other direction, at least a part of the compressedy air admitted to the receptacle being supplied above the mass of material in the receptacle.

14. In combination in a pneumatic conveyor, a casing having an inlet for material and an outlet at its lower side, a discharge line leading from said outlet, a gate at the entrance to said line pivoted at o ne edge 'and adapted to control the flow of material to the line, means for admitting air under pressure to the casing above the material therein, and means for admitting air under pressure to the space beneath the gate adj acent the pivoted edge thereof and directing such air lalong the lower side vof the gate' toward the free end thereof.

to the line, means for admitting air under pressure to the casing above the material therein, and means for admitting air under pressure to the space beneath the gate adjacent the pivoted edge thereof and directing such air along the lower lside of the gate toward the free end thereof, said gate fitting loosely in the casing so as to permit a flow of air past its margins in its various positions of adjustment. I A16. In combination in a concrete conveyor, a casing having an inlet for concrete at itsA upper side and an outlet at its lower side opening into a discharge line, a gate pivotally mounted within the casing with its free end toward the outlet yand the pivot away from the outlet, said gate being adapted to control the flow of concrete through the outlet, a partition in inclined position over the gatewithV its outer end extending over and protecting the pivoted edge of the gate from the concrete, whereby said partition and gate constitute a How line path for the concrete` toward the outlet and whereby said partition and gate provide a submerged air chamber within the casing, means for supplying air under pressure to the casing above the partition to cause a flow thereof toward the outlet and along theup'per surface of the gate, and means for admitting air under pressure to the casing below said partition. Y

17 In combination in aconcrete-conveyor,

a casing having an inletfor1concrete atits upper side' and an outlet at its lower side opening into a discharge line, an inclined partition extending from one of the si de walls of the casing toward said outlet, so that the upper face of the partition forms a slide for` l the concrete and the lower surface of the partition forms the roof of an air chamber, meansv forsupplying air under pressure to the casing above the partition to cause a flow thereof toward the outlet and over the partition, and means for supplying air under pressure immediately below the partition.

In testimony whereof, I have hereunto subscribed my name this 7th day of May,` 1931.

. 1 ALEXIS SAURBREY. 

